Fill a large stock pot with water and toss in the prepared potatoes and garlic. Set over moderate heat and bring to a boil, cooking until the spuds are fork-tender. Drain thoroughly before transferring the cooked potatoes to the bowl of your food processor.* Toss in the margarine and both cheeses, pureeing until smooth. Add salt and pepper to taste, and thin out with non-dairy milk if necessary. Continue processing for an additional minute or two, until silky, ribbon-like strands form when scooped up with a spoon.

Serve immediately while still hot.

*Yes, I did say food processor. This breaks all the known rules of mashed potato-making, but remember, this is aligot, not mashed potatoes. You want them to end up rather sticky, stretchy, and gooey.